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refactor: update stats/incr/wmean to handle nonnegative weights #4920

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refactor: update stats/incr/wmean to handle nonnegative weights #4920

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c9a6ad4
refactor: update wmean implementation and tests to handle nonnegative…
anandkaranubc Jan 27, 2025
6d48a4b
refactor: improve error message
anandkaranubc Jan 27, 2025
12552c5
refactor: apply suggestions from PR review
anandkaranubc Jan 28, 2025
f85aedd
docs: update the ts index file
anandkaranubc Jan 28, 2025
29d359f
Merge remote-tracking branch 'upstream/develop' into fix/wmean
stdlib-bot Feb 17, 2025
a0a1d52
Merge remote-tracking branch 'upstream/develop' into fix/wmean
stdlib-bot Apr 30, 2025
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3 changes: 2 additions & 1 deletion lib/node_modules/@stdlib/stats/incr/wmean/docs/types/index.d.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,8 @@
* - If provided `NaN` or a value which, when used in computations, results in `NaN`, the accumulated value is `NaN` for all future invocations.
*
* @param x - value
* @param w - weight
* @param {NonNegativeNumber} [w] - weight
* @throws {TypeError} second argument must be a nonnegative number
* @returns weighted arithmetic mean
*/
type accumulator = ( x?: number, w?: number ) => number | null;
Expand Down
17 changes: 16 additions & 1 deletion lib/node_modules/@stdlib/stats/incr/wmean/lib/main.js
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Expand Up @@ -18,6 +18,14 @@

'use strict';

// MODULES //

var isNonNegativeNumber = require( '@stdlib/assert/is-nonnegative-number' ).isPrimitive;
var format = require( '@stdlib/string/format' );


// MAIN //

/**
* Returns an accumulator function which incrementally computes a weighted arithmetic mean.
*
Expand Down Expand Up @@ -97,7 +105,8 @@ function incrwmean() {
*
* @private
* @param {number} [x] - value
* @param {number} [w] - weight
* @param {NonNegativeNumber} [w] - weight
* @throws {TypeError} second argument must be a nonnegative number
* @returns {(number|null)} weighted mean or null
*/
function accumulator( x, w ) {
Expand All @@ -107,6 +116,12 @@ function incrwmean() {
}
return mu;
}
if ( !isNonNegativeNumber( w ) ) {
throw new TypeError( format( 'invalid argument. Second argument must be a nonnegative number. Value: `%s`.', w ) );
}
if ( w === 0.0 ) {
return ( FLG === void 0 ) ? null : mu;
}
FLG = true;
wsum += w;
mu += ( w/wsum ) * ( x-mu );
Expand Down
58 changes: 42 additions & 16 deletions lib/node_modules/@stdlib/stats/incr/wmean/test/test.js
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Expand Up @@ -46,6 +46,47 @@ tape( 'the initial accumulated value is `null`', function test( t ) {
t.end();
});

tape( 'the accumulator function ignores zero weights and only updates the mean after encountering a non-zero weight', function test( t ) {
var acc = incrwmean();
t.equal( acc(), null, 'returns expected value' );
t.equal( acc( 2.0, 0.0 ), null, 'returns expected value' );
t.equal( acc( 2.0, 2.0 ), 2.0, 'returns expected value' );
t.equal( acc( 5.0, 0.0 ), 2.0, 'returns expected value' );
t.end();
});

tape( 'the accumulator function throws an error if provided a second argument which is not a nonnegative number', function test( t ) {
var values;
var acc;
var i;

values = [
'5',
-5.0,
NaN,
undefined,
true,
false,
null,
void 0,
[],
{},
function noop() {}
];

for ( i = 0; i < values.length; i++ ) {
t.throws( badValue( values[i] ), TypeError, 'throws an error when provided '+values[i] );
}
t.end();

function badValue( value ) {
return function badValue() {
acc = incrwmean();
acc( 2.0, value );
};
}
});

tape( 'the accumulator function incrementally computes a weighted arithmetic mean', function test( t ) {
var expected;
var actual;
Expand Down Expand Up @@ -99,24 +140,9 @@ tape( 'if not provided arguments, the accumulator function returns the current w
t.end();
});

tape( 'if not provided a weight, the accumulator function returns `NaN`', function test( t ) {
tape( 'if provided `NaN` for a value, the accumulator function returns `NaN`', function test( t ) {
var acc = incrwmean();
t.equal( isnan( acc( 2.0 ) ), true, 'returns NaN' );
t.equal( isnan( acc( 3.14 ) ), true, 'returns NaN' );
t.end();
});

tape( 'if provided `NaN` for either a value or a weight, the accumulator function returns `NaN`', function test( t ) {
var acc = incrwmean();
t.equal( isnan( acc( 2.0, NaN ) ), true, 'returns NaN' );
t.equal( isnan( acc( 3.14, NaN ) ), true, 'returns NaN' );

acc = incrwmean();
t.equal( isnan( acc( NaN, 1.0 ) ), true, 'returns NaN' );
t.equal( isnan( acc( NaN, 1.0 ) ), true, 'returns NaN' );

acc = incrwmean();
t.equal( isnan( acc( NaN, NaN ) ), true, 'returns NaN' );
t.equal( isnan( acc( NaN, NaN ) ), true, 'returns NaN' );
t.end();
});